Abstract: A multimedia fugacity model (level Ⅲ) was used to simulate the concentration distribution of chlorobenzene from Shaokou section to Songhua River Village section of the Second Songhua River based on a steady-state assumption. The concentration distribution was calculated in the air, water, suspended substance and the sediment. The results showed that the model output concentration in the air, water, suspended substance and the sediment were counted for 1.448×10-2 mg/m³,9.503×10-5 mg/L, 3.043×10-6g/kg (dw), 1.270×10-5g/kg respectively, when chlorobenzene was discharged to the water from pollution sources at 20mol/h of which chlorobenzene in the air was 94.931% in total, which indicated that after reaching steady-state in the system, chlorobenzene mainly existed in the air. In water environment, chlorobenzene distribution were 98.362% in water phase, 0.020% in suspended substance phase and 1.618% in sediment phase, respectively, which means that most chlorobenzene in water environment existed in the water phase and few in the suspended substance and the sediment phase.